The document discusses attribute based encryption and predicate encryption. It summarizes that attribute based encryption allows decryption of a ciphertext only if the attributes in the key match those in the ciphertext. Predicate encryption is a modification where keys are associated with predicates or functions, and a ciphertext can be decrypted if its attribute satisfies the key's predicate. The author's work involved developing predicate based encryption schemes in the public and private key settings, proving their security, and making them more efficient than existing schemes, though relying on stronger assumptions. Future work aims to base the schemes on weaker assumptions and improve efficiency further.

1. Attribute Based Encryption
B.Saikrishna
S.N.Bose Scholars Program Summer Research Internship.
Guided by Prof. Manoj Prabhakaran and Shashank Agrawal.
July 26,2013
B.Saikrishna (IIT-Madras) July 26,2013 1 / 12

2. What is cryptography?
1 Secure communication.
2 Protection from third parties or “adversaries”.
B.Saikrishna (IIT-Madras) July 26,2013 2 / 12

3. Applications
1 Online Banking
2 Cloud storage
3 Security of the entire digital world!
B.Saikrishna (IIT-Madras) July 26,2013 3 / 12

4. Encryption and Decryption
1 Encryption is the conversion of plaintext data into a form from which
the underlying plaintext cannot be recovered by anyone not
authorised to recover it.
2 Decryption is the process by which the underlying plaintext message
is recovered from an encrypted ciphertext.
B.Saikrishna (IIT-Madras) July 26,2013 4 / 12

5. Private Key Cryptography
B.Saikrishna (IIT-Madras) July 26,2013 5 / 12

6. Public Key Cryptography
B.Saikrishna (IIT-Madras) July 26,2013 6 / 12

7. Attribute Based Encryption
1 A paradigm in which the decryption of a ciphertext is possible only if
the attributes in the key match the attributes in the ciphertext.
2 An attribute could be anything. Example :
location,name,designation,etc.
3 A popular use of this is in the case of organisations.
B.Saikrishna (IIT-Madras) July 26,2013 7 / 12

8. Other Applications Of ABE
1 Cloud storage and retrieval.
2 To outsource complex computations to a cloud device,while also
maintaining secrecy of data.
B.Saikrishna (IIT-Madras) July 26,2013 8 / 12

9. Predicate Encryption
1 A modification of ABE where keys are associated with
“predicates”(functions).
2 A ciphertext can be decrypted by a key if the attribute within the
ciphertext satisfies the function present in the key.
3 We worked with functions called “inner products” which are similar to
the vector dot products.
4 Ultimate goal is to realise all “polynomial time ” functions.
B.Saikrishna (IIT-Madras) July 26,2013 9 / 12

10. Our Work
1 Predicate Based encryption schemes in the public and private key
settings.
2 We prove our schemes to be secure under different notions of
security- attribute hiding , predicate hiding.
3 More efficient than the currently existing schemes( in terms of size
and amount of computation needed)
4 On the downside,we use “stronger” assumptions.
B.Saikrishna (IIT-Madras) July 26,2013 10 / 12

11. Future Work
1 To base our schemes on “weaker” and lesser assumptions.
2 To improve the efficiency even more.
B.Saikrishna (IIT-Madras) July 26,2013 11 / 12

12. Thank you!
B.Saikrishna (IIT-Madras) July 26,2013 12 / 12